Die casting apparatus

ABSTRACT

The invention relates to heater apparatus for controlling the temperature of the melt within the nozzle or transfer tube of a die casting machine. The apparatus employs thermostaticallycontrolled heated gases which flow into an enclosure surrounding the nozzle, maintain the nozzle within a predetermined temperature range, and are either exhausted from the enclosure or are recycled back to the heater. The enclosure includes a damper deflector and walls which are readily retractable for access to the nozzle.

United States Patent 1191 Jones [111 3,809,531 145 May 7, 1974 DIECASTING APPARATUS Melvin A. Jones, Lake Mohawk R.R. No. l, Tiffin, Ohio44883 Filed: June 4, 1973 Appl. No.: 366,645

Inventor:

U.S. c1.....-.. 432/225, 432/227 161. c1. F27b 9/36 Field 61 Search432/222, 225, 226, 227,

432/219; 164/250; l8/DIG. 39

References Cited UNITED STATES PATENTS 12/1972 Mulhall 432/219 9/1969Blinne 432/225 9/1965 Bennett et al. 432/219 Primary Examiner-John J.Camby Attorney, Agent, or Firm-Thomas M. Freiburgcr;

Richard D. Emch; Owen & Owen [5 7] ABSTRACT The invention relates toheater apparatus for control ling the temperature of the melt within thenozzle or transfer tube of a die casting machine. The apparatus employsthermostatically-controlled heated gases which flow into an enclosuresurrounding the nozzle, maintain the nozzle within a predeterminedtemperature range, and are either exhausted from the enclosure or arerecycled back to the heater. The enclosure includes a damper deflectorand walls which are readily retractable for access to the nozzle.

7 Claims, 4 Drawing Figures 1 DIE CASTING APPARATUS BACKGROUND OF THIEINVENTION Various means have been employed for controlling the melttemperature within the nozzle of a hot chamb er die casting machine. Oneof these prior art means is a set of electric resistance heaters orCalrods encased in a clamshell type device which surrounds the nozzle.There are many disadvantages to the use of these'devices.

The electric resistance units are not responsive to the need forfrequent access to the nozzle in that they are generally not readilyremovable from around the nozzle. They are quite fragile and tend todevelop breaks after repeated removal and replacement.

Another disadvantage of the electric resistance units is their slowresponse to the changing demands of the nozzle for heat. In addition,the units tend to result in quite localized heating of the nozzle withmuch local overheating, so that the temperature of the melt is notevenly controlled and the nozzle itself is subjected to considerablestresses. These stresses weaken the nozzle and eventually cause cracksand breaks which shorten nozzle life and create a safety hazard forthose in the vicinity.

Another prior art means of maintaining nozzle temperature control is theuse of a blow torch. Not only does the blow torch, like the electricunits, tend to result in uneven heating, but it is'also generally quiteunwieldly and somewhat hazardous. This form of heating also tends toerode the nozzle. Bends or cracksmay develop due to the unevenness ofthe application of the heat, and often a torch left unattended willactually melt a portion of the nozzle. Accordingly, the operatorgenerally does not leave the vicinity of the nozzle with a torch inoperation.

SUMMARY OF THE INVENTION The present invention provides an improvedheater apparatus or nozzle melt control for a die casting machinevirtually free of the disadvantages inherent in prior art nozzleheaters. The invention employs thermostatically-controlled hot gaseswhich enter the vicinity of the nozzle or transfer tube, evenly maintainthe nozzle within a predetermined temperature range, and then eitherpass into the surrounding air or return to the heater. The heating ofthe gas is accomplished by means of a hydrocarbon fuel burning devicewhich is thermostatically controlled. The hot gas is led to the exteriorof the nozzle through a conduit that terminates in an enclosuresurrounding the nozzle.

In addition to containing the hot gases, the enclosure provides a safetyshield which will block the ejection of molten metal in the event of afailure of the nozzle. Within the enclosure is a thermocouple which isconnected to the thermostat control of the combustion chamber. Thesystem preferably includes a blower, which may be of the variable speedtype, for frocing the hot gases to the enclosure. The enclosure alsoincludes a damper-like deflector for adjusting the distribution of thehot gases around various portions of the nozzle. For example, during aperiod when the hot chamber die casting machine is inactive use, it maybe desirable to deflect most of the hot gas to the end of the nozzleadjacent the dies, because the melt in the other end of the nozzle willbe kept relatively hot from the repeated the length of the hozzle.

flow of the melt from the gooseneck or the pot. Conversely, if the diecasting apparatus is inactive or in infrequent use then a more equaldistribution over the length of the nozzle is more desirable.

The nozzle enclosure includes retractable side an end portions adjacentthe nozzle for quick and easy access to the nozzle. These retractableportions are preferably hinged and when in closed position are retainedtogether by use of spring clamp fasteners of the toggle action type.This accessibility feature of the present invention provides'anadvantage over prior art calrod type nozzle heaters, which are normallynot easily removed and replaced.

The enclosure provides several exhaust ports through which the hot gasesexit after their communication with thenozzle or transfer tube.Preferably an exhaust port is located in each end of the enclosure,concentric with a haust ports, together with the damper-like deflector,

helps facilitate even heat applicationaround the periphery of the nozzlewith the desired distribution along The end exhaust ports facilitatedistribution of hot gases to portions of the nozzle beyond the enclosureand beyondareas reachable by prior art resistance unit heaters. Thegooseneck itself, above the surface of the melt in the pot, requiresheat in some circumstances to prevent freezing of the melt in that area.The present heater can provide such heating'by directing gases out theexhaust port in the direction of the nozzle. Satisfactory resistanceunit type heaters have not been available for this purpose. Essentiallythe only method of remelting metal in the gooseneck has been by means ofthe torch with its above-discussed disadvantages.

Similarly, the opposite end of the nozzle may be heated in its entirety,through the platen and up to the die cavity. This is possible because ofthe ability of hot gases to flow in a tortuous path and generallywherever they are directed. Conventional resistance unit heaters couldnot be placed on this extremity because of lack of space around thenozzle. Because the present heater with its end exhaust ports is capableof directing hot gases to areas far beyond the limits of its enclosure,it is especially versatile in being applicable to a relatively widerange of nozzle lengths.

For different nozzle diameters, the heater apparatus may be providedwith various side and end portions, re-

movable at the hinges, so that the end exhaust ports may be of suitablediameter with predetermined opening area.

When the enclosure includes exhaust ports as discussed above, the hotgas medium is preferably air.

However, it is sometimesdesirable to recirculate the gas rather thanexhausting hot gases in the vicinity of the die casting machine. In thatcase, the exhaust ports are replaced by conduits leading back toward thecombustion chamber. The system is then substantially 7 closed and can becharged witheither air or any other I BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 diagrammatically indicates a hot chamber submerged plunger diecasting apparatus with a nozzle heated by heater apparatus according tothe present invention; 7

FIG. '2 is a sectional view of a nozzle enclosure portion of the presentinvention taken along the line 2-2 of FIG. 1; I

FIG. 3 is a partially sectioned, diagrammatic elevational view of avertical cold chamber type die casting apparatus in which an embodimentof the invention is employed to maintain the melt in the transfer tubewithin a predetermined temperature range; and

FIG. 4 is a partially sectioned diagrammatic side view of a heaterapparatus embodying the instant invention and including a recirculatingmeans.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 indicates a hot chamberdie casting machine including a nozzle heated by a heater apparatusembodying the present invention and generally indicated by the referencenumber 10. The heater apparatus is constructed almost entirely of sheetmetal. The apparatus 10 includes a blower 11, preferably of the variablespeed type. Makeup air is forced through a burner chamber generallyindicated by the reference number 12, preferably a natural gas burner.Other types of heating means may be used in the chamber 12, for example,electrical resistance type units. The burner is controlled by athermostat control 13 and may be set at various temperature levels. Fromthe burner chamber, 12, the heated air passes through an angled conduit14 and into a nozzle enclosure 15-which is spaced from a nozzle 16. Theangled conduit 14 may be replaced by a straight conduit 17, dependingupon the positioning of the nozzle 16. As the air enters the enclosure15, it passes over a thermocouple sensor 18 to which the thermostatcontrol 13 is responsive.

As shown in FIGS. 1 and 2, the enclosure 15 provides a continuous bathof hot air enveloping andevenly heating thenozzle 16. Tapered endportions 19 and 20 and exhaust ports 21 and 22 assure that thedistribution of hot air includes the extremities of the nozzle 16.

Spacers 23' at several points around the circumference of the exhaustports 21 and'22 assure equal peripheral spacing from the nozzle 16, andthus even flow over-the portions of the nozzle 16 outside the enclosure15. In order that the distribution of hot air may be varied along thelength ofthe nozzle 16, a variable damper deflector 24 is includedwithin the enclosure 15. The deflector 24 is preferably manuallyoperated but may include automatic adjusting means (not shown) sensitiveto changes in temperature along the length of the nozzle l6.

The enclosure 15 has retractable side portions 25 and 26 and retractableend flaps 27 and 28, all of which are preferably pivotally retained toan upper portion 29 of the enclosure 15 by hinges 30. Toggle actionspring clamp fasteners 31 provide readily removable fastening means. Theside portions 25 and 26 include exhaust ports 32 below the nozzle 16 tosupplement the exhaust ports 21 and 22 defined by the end portions 19and 20.

Referrin g'to FIG. 3, another embodiment of heater apparatus 10a isshown in connection with a vertical cold chamber type die castingmachine generally indicated by the reference number 33. The machine 33employs a vacuum to move the molten metal 34 from the pot 35 through thetransfer tube 36 and into the shot sleeve 37. In the claims the termnozzle is utilized in its generic sense to include melt conduits such asthe transfer tube 36. The heater apparatus 10a has a straight conduit 17rather than the angled conduit 14 of FIG. 1. The heater apparatus 10a isused to maintain the molten metal '34 in, the transfer tube 36 within apredeterminedtemperature range. It will be appreciated that theembodiments are applicable to any die casting machine wherein moltenmetal is moved from a pot through a transfer tube or nozzle andultimately into a die cavity.

In FIG. 4 a heater apparatus 38, embodying the'invention, is shown withrecirculating means generally indicated by the reference number 39. Thisembodiment includes recirculation ports-40 and'41 in an enclosure 42rather than the exhaust ports 21, 22, and 32 of the enclosure 15 of theFIG 1 embodiment. Each tapered end portion 43 of the enclosure 42 isfitted to closely circumscribe the nozzle or transfer tube 44 and mayinclude a ring of asbestos 45 to sealingly enclose the nozzle ortransfer tube '44. The recirculating conduit 38 preferably includesdetachable joints 46 and pivotal joints 47 so that the hinged sideportions 48 re main readily retractable for access to the nozzle ortransfer tube 44. The conduit 39 has valving means 49 and 50 whereby thevolume of recirculated gases may be varied, with a portion of the gasesbeing recirculated to the burner chamber and the remainder discharged tothe atmosphere.

The above described preferred embodiments provide a heater apparatus ora melt control system. capable of evenly heating a nozzle or transfertube and the melt therein and maintaining them within a predeterminedtemperature range. The system provides easy access to the nozzle and issafe, compact, efficient, and economii cal. Various other embodimentsand changes to the preferred embodiments described above will beapparent to those skilled in the art,and may be made without departingfrom the spirit and scope of the following claims.

What I claim is:

1. Heater apparatus for use with a die casting machine having a nozzlefor transmitting the melt to the dies, said heater apparatus comprisingheating means for heating a gas, enclosure means surrounding and spacedfrom the nozzle for effecting fluid communication between the heated gasand the nozzle and even heating around the nozzle, adjustable meanswithin said enclosure means for selectively distributing the'hea'ted gasalong the nozzle, a conduit extending between said heating means andsaid enclosure means defining a path of gas travel, blower means incommunication with said conduit for transferring the gas from saidheating means to said enclosure means, means for disposing of the gasafter its communication with the nozzle, and means for regulating thetemperature ofthe gas within said enclosure means.

2. Heater apparatus according to claim I wherein I said adjustable meanscomprises a damper deflector pivotally mounted within said enclosuremeans adjacent said conduit in the path of gas travel.

munication betweenthe gas and the nozzle outside said enclosure means.

6. Heater apparatus according to claim 1 wherein said gas disposingmeans includes means for recirculating the gas from said enclosure meansto said heating means.

7. Heater apparatus according to claim 6 wherein said gas recirculatingmeans comprises a returngas conduit leading from said enclosure means tosaid heating means.

1. Heater apparatus for use with a die casting machine having a nozzlefor transmitting the melt to the dies, said heater apparatus comprisingheating means for heating a gas, enclosure means surrounding and spacedfrom the nozzle for effecting fluid communication between the heated gasand the nozzle and even heating around the nozzle, adjustable meanswithin said enclosure means for selectively distributing the heated gasalong the nozzle, a conduit extending between said heating means andsaid enclosure means defining a path of gas travel, blower means incommunication with said conduit for transferring the gas from saidheating means to said enclosure means, means for disposing of the gasafter its communication with the nozzle, and means for regulating thetemperature of the gas within said enclosure means.
 2. Heater apparatusaccording to claim 1 wherein said adjustable means comprises a damperdeflector pivotally mounted within said enclosure means adjacent saidconduit in the path of gas travel.
 3. Heater apparatus according toclaim 1 wherein said enclosure means includes retractable portions forproviding ready accessibility to the nozzle.
 4. Heater apparatusaccording to claim 3 wherein said retractable portions are hinged. 5.Heater apparatus according to claim 1 wherein said enclosure meansincludes forward and rearward end portions circumscribing the nozzle andwherein said gas disposing means comprises exhaust ports, at least oneof which is positioned peripheral to the nozzle in one of said endportions for effecting further communication between the gas and thenozzle outside said enclosure means.
 6. Heater apparatus according toclaim 1 wherein said gas disposing means includes means forrecirculating the gas from said enclosure means to said heating means.7. Heater apparatus according to claim 6 wherein said gas recirculatingmeans comprises a return gas conduit leading from said enclosure meansto said heating means.